1. Field of the Invention
The present invention relates to a tape carrier package which is attached to the periphery of a liquid crystal panel of a liquid crystal display device and accommodates a semiconductor chip for driving the liquid crystal panel on a tape carrier, and a liquid crystal display device provided with tape carrier packages.
2. Description of the Related Art
Conventional liquid crystal display devices, as shown in FIG. 10, have been known. This liquid crystal display device 150 is mainly composed of a liquid crystal panel 100, a plurality of tape carrier packages (TCPs) 117, and a common printed wiring board 118. The liquid crystal panel 100 is mainly composed of an upper glass substrate 110, a lower glass substrate 111, and a liquid crystal layer (not shown) interposed therebetween. Reference numeral 122 denotes a flexible substrate.
In this liquid crystal display device, as shown in FIG. 13, the semiconductor chips 104 for driving the liquid crystal are mounted onto the liquid crystal panel 100 as follows: a tape carrier with semiconductor chips 104 placed thereon is cut to a predetermined size to obtain TCPs 117; each TCP 117 is supplied onto the liquid crystal panel 100; and a conductive pattern portion (e.g., outer leads) of each TCP 117 and electrodes on the lower glass substrate 111 of the liquid crystal panel 100 are crimped onto each other by heating with an anisotropic conductive film 140 interposed therebetween, whereby each TCP 117 is mounted onto the liquid crystal panel 100.
As shown in FIG. 13, outer leads (not shown) of the TCPs 117 are connected to wiring (not shown) of the printed wiring board 118. A signal for driving the liquid crystal is supplied to each semiconductor chip 104 through each TCP 117 from the printed wiring board 118. The printed wiring board 118 also has a region 118a for accommodating components, such as a chip capacitor, which cannot be incorporated into the circuit of each semiconductor chip 104.
FIG. 11 is a cross-sectional view of another liquid crystal display device 160 with a TCP 117xe2x80x2 attached to the periphery of a liquid crystal panel 100. The TCP 117xe2x80x2 is attached to the liquid crystal panel 100 as follows: an output terminal 117a of the TCP 117xe2x80x2 for driving the liquid crystal is connected to the liquid crystal panel 100 via an anisotropic conductive film 140; thereafter, an input signal terminal 117b of the TCP 117xe2x80x2 is connected to a printed wiring board 118 by soldering or via an anisotropic conductive film 140xe2x80x2; and the TCP 117xe2x80x2 is bent along the contour of a module, whereby the attachment of the TCP 117xe2x80x2 to the liquid crystal panel 100 is complete. In FIG. 11, reference numeral 119 denotes a backlight unit; 120 denotes a polarizing plate; and 116 denotes a bezel.
It is also known that a semiconductor chip is attached to a liquid crystal panel by a Chip-On-Glass (COG) method. According to the COG method, as shown in FIG. 12, a semiconductor chip 104 having metal bumps 104a is directly connected to wiring (not shown) on a lower glass substrate 111 by face down bonding. Regarding the COG method, the following two processes are known.
Firstly, a semiconductor chip having solder bumps is directly attached to a glass substrate of a liquid crystal panel, and then, a gap between the semiconductor chip and the glass substrate is filled with a resin (Japanese Laid-Open Patent Publication No. 4-105331). Secondly, a semiconductor chip having gold bumps is connected to wiring on a glass substrate of a liquid crystal panel via an anisotropic conductive film 121 (Japanese Laid-Open Patent Publication Nos. 4-76929, 4-71246, and 4-317347). In the case of the second process, a gap between the semiconductor chip and the glass substrate is filled with a resin (binder) of the anisotropic conductive film. According to the second process, repairs are easily conducted, and it is not required to fill a resin in the gap between the semiconductor chip and the glass substrate; therefore, this process has been mainly used.
In recent years, there is a tendency to secure a larger display area with the same module size by decreasing the width of the portion of a liquid crystal display device that extends off a glass substrate. Furthermore, there is a great demand for a reduction in costs for liquid crystal panels in light of the generally, higher production costs compared with those of CRTs (Cathode Ray Tube).
Under such circumstances, in order to decrease the width of a TCP which extends off a glass substrate, the following two methods using TCPs have been proposed: (1) A slim-type TCP 117 with a narrow semiconductor chip formed thereon is used, as shown in FIG. 13 (Japanese Design Patent Application No. 2-40145); and (2) as described with reference to FIG. 11, a portion of a TCP 117xe2x80x2 which extends off a glass substrate is bent (Japanese Laid-Open Patent Publication No. 2-132418).
According to the method shown in FIG. 13, a material used for a TCP itself is also reduced, which contributes to a reduction in costs. However, it is necessary to decrease the width of a printed wiring board in accordance with the width of a portion of a TCP which extends off a glass substrate. When the width of the printed wiring board is decreased without changing the wiring density, it is necessary to increase the number of layers of the printed wiring board. This results in an increase in costs. In addition, since the width of a connected portion of the printed wiring board and the TCP is very small, it is difficult to mount the TCP onto the printed wiring board. This may adversely influence the yield and reliability of the semiconductor device. These problems become serious in circumstances where liquid crystal panels are increasing in size.
As shown in FIG. 13, even when the above-mentioned slim-type TCP is used, a portion with a width of about 5 mm necessarily extends off the glass substrate. FIG. 10 is a schematic plan view (the bezel 116 is omitted) of a liquid crystal panel constructed as illustrated in FIG. 13.
In the case where the bent TCP 117xe2x80x2 is used, as shown in FIG. 11, the printed wiring board 118 may be provided either on the upper surface or on the lower surface of the lower glass substrate 111. In the case where the printed wiring board is provided on the lower surface of the lower glass substrate 111, the wiring of the liquid crystal panel 100 can be connected to the printed wiring board 118 via the bent TCP 117xe2x80x2. Therefore, the printed wiring board 118 need not extend beyond the liquid crystal panel 100. Accordingly, the problem associated with large size devices can be solved to some degree. In the case shown in FIG. 11, the width of a portion of the TCP which extends off the glass substrate is only 2 mm (which is much smaller than that in the case as shown in FIG. 13).
However, in the case of using the bent TCP 117xe2x80x2, there are the following problems: the length of the TCP 117xe2x80x2 must be larger by the bent portion thereof, so that the costs for a tape carrier portion of the TCP 117xe2x80x2 are higher; it is easier to connect the printed wiring board 118 to the TCP 117xe2x80x2 compared with the case where the above-mentioned slim-type TCP 117 is used, however, the TCP 117xe2x80x2 must be bent to a predetermined shape after the TCP 117xe2x80x2 is connected to the printed wiring board 118, so that the TCP 117xe2x80x2 is fixed to the printed wiring board 118, so that the TCP 117xe2x80x2 is fixed to the printed wiring board 118; and the thickness of a liquid crystal module becomes larger by the total thickness of the printed wiring board 118 and the TCP 117xe2x80x2 (i.e., about 2.5 mm to 3 mm), compared with the case where the slim-type TCP 117, as shown in FIG. 13, is used.
According to the COG method, a semiconductor chip is directly mounted onto a glass substrate, so that the costs for packaging are less, compared with the case where a TCP is used. Furthermore, when an input signal is adapted to be supplied to a semiconductor chip via wiring on a glass substrate, a printed wiring board is not required. This results in a decrease in costs. Still furthermore, according to the COG method, a semiconductor chip is merely mounted onto a glass substrate, so that the costs for mounting can be reduced.
However, the above-mentioned advantages cannot be obtained from currently used large liquid crystal panels with a 10-inch or more diagonal screen for the following reason: the sheet resistance of the wiring material on a glass substrate is high; therefore, in the case where an input signal is supplied to a semiconductor chip via wiring on the glass substrate, the wiring resistance cannot be minimized; and as a result, voltage drops in the wiring, which makes it impossible to transmit a normal signal to a semiconductor chip. In relatively small liquid crystal panels with about a 3- to 6-inch diagonal screen, the wiring length is small, so that the material sheet resistance is negligible. Accordingly, the above-mentioned advantages can be obtained only from relatively small liquid crystal panels.
However, when the above-mentioned structure is applied to small liquid crystal panels using the COG method, there are the following problems: since it is required to prescribe the width of wiring on a glass substrate to be large, the area of the glass substrate for mounting semiconductor chips is required to be made larger, compared with the case where TCPs are used; this requires the size of the glass substrate to be increased. In this case, the number of liquid crystal panels obtained from mother glass decreases. Thus, even in the case where the COG method is used for small liquid crystal panels, cost is not likely to decrease as far as an entire module is concerned.
In order to solve the problem associate with the enlargement of an area of a glass substrate for mounting semiconductor chips, as shown in FIG. 12, it is possible to adopt a method for directly connecting a flexible substrate 122 to the wiring on a glass substrate in the vicinity of a portion for mounting each semiconductor chip 104 and transmitting an input signal from the flexible substrate 122. (Japanese Laid-Open Utility Model Publication No. 4-77134). According to this method, a printed wiring board is not required, however, the flexible substrate 122 is used. Therefore, advantages in terms of lower production costs and fewer steps cannot be obtained.
Furthermore, according to the COG method, bare chips are supplied onto a glass substrate. The bare chips are generally tested in a wafer state, and they are not tested after being divided into individual chips by dicing. Thus, it is difficult to judge whether or not a particular semiconductor chip to be mounted onto a glass substrate is satisfactory. That is, a semiconductor chip to be mounted is not a xe2x80x9cknown good die.xe2x80x9d Because of this, in the case of a large liquid crystal panel in which a number of semiconductor chips are mounted, there are more chances of failures and repairs, resulting in an increase in costs.
A tape carrier package of the present invention includes: a tape carrier including an insulating film having a through-hole, a conductor pattern formed on the insulating film including leads projecting into the through-hole, and inner wiring electrically connected to a part of the conductor pattern; a semiconductor chip provided in the through-hole, having connecting bumps electrically connected to end portions of the leads; and an anisotropic conductive resin provided so as to cover at least a portion of the semiconductor chip including a junction of the connecting bumps and the end portions of the leads.
In one embodiment of the present invention, the anisotropic conductive resin is made of an insulating resin containing fine particles having conductivity, and the insulating resin is selected from the group consisting of a thermosetting resin, a UV-curing resin, and a thermoplastic resin.
In one embodiment of the present invention, the semiconductor chip includes intra-chip wiring and at least one bump for the intra-chip wiring.
In one embodiment of the present invention, an electronic device different from a semiconductor chip is mounted on the inner wiring provided on the tape carrier.
The liquid crystal display device of the present invention comprising: a liquid crystal panel including a pair of glass substrates and connecting wiring formed on at least one of the glass substrates; and at least two tape carrier packages mounted on a periphery of the liquid crystal panel, wherein each tape carrier package comprises: a tape carrier including an insulating film having a through-hole, a conductor pattern formed on the insulating film including leads projecting into the through-hole; a semiconductor chip provided in the through-hole, having connecting bumps electrically connected to end portions of the leads; and an anisotropic conductive resin provided so as to cover at least a portion of the semiconductor chip including a junction of the connecting bumps and the end portions of the leads, and the connecting bumps on the semiconductor chip of the tape carrier package and the connecting wiring of the glass substrate are electrically connected via the anisotropic resin provided on the tape carrier packages, thereby signals can be transmitted/received between the semiconductor chips of the adjacent tape carrier packages.
In one embodiment of the present invention, the anisotropic conductive resin is made of an insulating resin containing fine particles having conductivity, and the connecting bumps of the semiconductor chip and the connecting wiring of the glass substrate are electrically connected via the fine particles having conductivity.
In one embodiment of the present invention, the semiconductor chip includes intra-chip wiring and at least one bump for the intra-chip wiring.
In one embodiment of the present invention, the tape carrier packages are mounted on the liquid crystal panel so that the tape carrier has a portion projecting from the liquid crystal panel, the projecting portion being bent.
In one embodiment of the present invention, the tape carrier packages are mounted on the liquid crystal panel so that the tape carrier has a portion projecting from the liquid crystal panel, at least a portion of the conductor pattern and the inner wiring which are formed on the projecting portion of the tape carrier being exposed, and a metal leads are provided so as to electrically connect the exposed portions of the adjacent tape carrier packages.
Thus, the invention described herein makes possible the advantages of (1) providing a tape carrier package in which a printed wiring board which has been conventionally required can be omitted and the consequent fabrication step of mounting of a printed wiring board can be omitted; and (2) providing a liquid crystal display device provided with tape carrier packages.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.